The present invention relates to a locking mechanism for releasably securing earth excavation teeth or points on a trenching machine. It is well-known to provide earth excavation equipment such as trenching machines with points that can be removed for replacement when they become worn or damaged. Such points are generally mounted on a large tapered nose piece which in turn are mounted on the bucket of a large rotating wheel on the trenching machine. These points are typically secured to the nose piece by one or more pins which extend through aligned channels in the point and nose piece. Historically, horizontally disposed pins were used for such purposes. However, when the teeth on such equipment became more closely spaced, it became difficult to insert and remove horizontal pins from adjacent teeth. Flex pin arrangements which extended vertically through the point and nose piece were then developed as a substitute for the horizontal pins. Examples of vertical flex pin assemblies are found in U.S. Pat. No. 4,231,173 and in applicant's copending application Ser. No. 501,520 filed June 6, 1983, now U.S. Pat. No. 4,516,340.
While the vertical flex pin attachments had several advantages over the old horizontal pins, they did not solve all of the problems inherent in the securement of points onto trenching machines. If a flex pin, whether it be adapted for horizontal or vertical disposition is mishandled and dropped during installation or removal, they fall into the trench, delaying the replacement operation. This is an all too frequent occurrence due to the difficulty in aligning and handling the nose piece, point and pin or pins. Secondly, the use of locking pins requires a precise fit between the pin, the nose and the point, and the upper surfaces of the point through which vertical pins are inserted are constantly covered with dirt during the trenching operation. Should dirt become lodged in the cooperating channels in the pin or nose piece, proper alignment of the locking pins becomes difficult. Improper alignment often results in breakage. Further, because the points on trenching machines are mounted on buckets secured to a large rotatable wheel, the upper surface of the tooth is generally inaccessible for as soon as the wheel moves the tooth to an accessible elevated position, the tooth becomes inverted on the wheel with the upper side thereof facing the ground. This orientation makes a vertical pin replacement a relatively awkward and time-consuming operation.
It would therefore be highly desirable to provide a locking mechanism for large teeth on trenching equipment which retains the advantages of the vertically disposed flex locking pins, but which obviates their handling difficulties and which removes the mechanism from the upper surface of the point which is both inaccessible on such equipment and in constant contact with the dirt during the trenching operation.